runtime benchmark program checked in

[Martin Hunt]

This is meant as a tool to measure the performance of various runtime
functions, as well as kprobes and jprobes.  I have just a few
measurements working so far.

see src/runtime/probes/bench/README

sample output:

STP BENCH for 2.6.9-11.14.EL.huntsmp on x86_64
 14:34:55 up  4:34,  7 users,  load average: 0.02, 0.10, 0.13
processors: 4 (2 physical) Intel(R) Xeon(TM) CPU 2.80GHz
--------------------------------------
Jprobes overhead = 2393 ns
Kprobes overhead = 1489 ns
--------------------------------------
Return probe overhead       = 2164 ns
Entry+Return probe overhead = 2174 ns
--------------------------------------
2 kprobes on same func       = 1533 ns
4 kprobes on same func       = 1548 ns
--------------------------------------
NETLINK
_stp_printf on 100 chars = 6031 ns
_stp_print  on 100 chars = 6290 ns
--------------------------------------
RELAYFS
_stp_printf on 100 chars = 977 ns
_stp_print  on 100 chars = 1369 ns
--------------------------------------

Note that the NETLINK and RELAYFS numbers will change as we tune them.

Martin